1. Field of the Invention
The present invention relates generally to shoe soles, and, more particularly, to a shoe sole which has functions of correcting a gait, of absorbing shocks, and of mitigating partial side wear of the sole.
2. Background Art
Shoes, which are a life necessity, have rapidly developed in function as well as in design. The design of the shoes is very important in arousing consumers' interest, and thus new products have been continuously proposed. Furthermore, recently, various functional shoes have been popularized. Special purpose shoes, which are used in exercise, or shoes having functions of curing or mitigating disorders of users are representative examples of such functional shoes.
Meanwhile, human beings who walk upright may congenitally or developmentally have an abnormal gait. Particularly, in the case of a user having a developmentally abnormal gait, if the abnormal gait is not corrected in an initial stage thereof, it may get worse.
According to the position of the foot with respect to the ground when the foot contacts the ground, the gait of humans is classified into a neutral gait, in which the foot perpendicularly contacts the ground, a pronation gait, in which the foot is inclined inwards, and a supination gait, in which the foot is inclined outwards.
In the case of a user having a pronation gait or a supination gait, if the user wears shoes that are manufactured for users having neutral gaits, the abnormal gait cannot be corrected, and may get worse instead. To correct the abnormal gait, the user must buy separate shoe insoles or shoe inserts suitable for his/her feet, or must use separate shoe insoles or shoe inserts which are manufactured at a relatively high cost in a special foot clinic. As such, due to the cost and time constraints, there is a problem in that it is difficult for a user having an abnormal gait to correct the gait.
Meanwhile, in the case where even a user having a neutral gait uses shoes for a long period, left and right portions of the heel of each shoe may wear unevenly. Such a partial side wear phenomenon of the heel of the shoe reduces the lifetime of the shoe, and may affect the gait of the user. In the case of a user having an abnormal gait, this problem is more clearly evident.
It is impossible to completely overcome the partial side wear phenomenon of the heel of the shoe sole. Therefore, in the conventional arts, various methods of merely compensating for or mitigating the partial side wear phenomenon have been proposed. Representative conventional techniques pertaining to this will be explained herein below.
Representatively, there are Korean Utility Model Registration No. 184556, Japan Patent Laid-open Publication No. Heisei. 9-224704, Japan Utility Model Laid-open Publication No. Sho. 61-179905, and U.S. patent Publication No. 2006-213082.
In U.S. patent Publication No. 2006-213082, a coil spring is provided in the heel of a shoe sole, and is covered with a platform, which is fastened into the heel in a thread coupling method. Thus, the height of the heel and the elastic force of the coil spring are adjustable. However, this technique has no gait correction function.
In the remaining conventional techniques, part of the heel is provided so as to be rotatable, so that, when partial side wear occurs, the part of the heel is rotated, thus preventing only a small portion of the heel from being excessively worn. These techniques merely mitigate the partial side wear phenomenon of the heels, but there is a technical limit in their ability to correct abnormal gaits.
Meanwhile, another related technique was proposed in U.S. Pat. No. 5,435,079, entitled “SPRING ATHLETIC SHOE”. FIG. 1 is a side view showing the spring athletic shoe of U.S. Pat. No. 5,435,079.
In this technique, part of a shoe sole is removed to form space therein, and a spring is provided in the space at a position corresponding to the heel of the shoe. The purpose of this technique is to provide sufficient shock absorbing ability. However, because the spring is fixed, it cannot be used for a purpose of correcting the gait.